The present 1nvention relates to a thin film magnetic head used in a magnetic recording/playback apparatus and a manufacturing method thereof, and more particularly to a thin-film magnetic head capable of thickly stacking a magnetic layer with retaining a size of an outward appearance of the head in order to prevent a magnetic circuit from a magnetic saturation and a method of manufacturing the thin-film magnetic head.
In general, a thin-film magnetic head has a magnetic layer, an insulating layer and a coil conductive layer which are formed step by step with a stack by means of a vacuum evaporation and etching, and is a smaller and thinner than a conventional bulk head. However, the thin-film magnetic head has the complicated processing steps, and it is impossible for the thin-film magnetic head to precisely keep outline sizes of completed products when the magnetic layer is thickly stacked in order to prevent the magnetic circuit from a magnetic saturation.
The conventional thin-film magnetic head is shown in FIG. 1. In the figure, a material 10 of a thin-film magnetic head 10A comprises a non-magnetic insulating substrate 11, a lower magnetic substance layer 12 which is stacked on a side of the substrate 11, a gap layer 13 which is stacked on a predetermined and limited area of the magnetic layer 12, a first insulating layer 14a which is stacked on a predetermined and limited area of the gap layer 13, a first coil layer 15a which is formed in line shapes of a plurality of rows on the first insulating layer 14a, a second insulating layer 14b which is stacked on the first insulating layer 14a in the manner of covering the first coil layer 15a, a second coil layer 15b which is formed on the second insulating layer 14b corresponding to the first coil layer 15a, a third insulating layer 14c which is stacked on the second insulating layer 14b in the manner of covering the second coil layer 15b, an upper magnetic substance layer 16 which is stacked in the manner of covering an insulating substance layer 14 including the first through third insulating layers 14a, 14b and 14c and a coil conductive layer 15 including the first and second coil layers 15a and 15b, and a protective layer 17 which is stacked on an upper surface of the upper magnetic substance layer 16.
As shown in FIG. 2, the material 10 stacked and configured as above, is cut in the outline shape of the thin-film magnetic head 10A so as to complete a product. The head 10A as the product has an outline in the manner of combining a small rectangular portion with a large rectangular portion, and a long side of the small rectangular portion is used as a tape contacting surface 10B.
The material 10 of the conventional thin-film magnetic head 10A is manufactured by some steps shown in FIGS. 3A through 3F. In a first step shown in FIG. 3A, the lower magnetic substance layer 12 which is made of amorphous, is stacked on the non-magnetic insulating substrate 11 which is made of abrasion resisting materials such as glass and ceramics.
Next, in a second step shown in FIG. 3B, the gap layer 13 which is made of materials of SiO.sub.2, Al.sub.2 O.sub.3 and the like and functions as a head gap of the magnetic head after completed, is stacked in the predetermined or limited area on the magnetic layer 12. Furthermore, the first insulating layer 14a which becomes one portion of the insulating substance layer 14 for insulating the coil conductive layer 15 which will be formed by a step mentioned later, is stacked on predetermined area of the gap layer 13.
In a third step shown in FIG. 3C, the first coil layer 15a is formed in a predetermined pattern. In this example, the coil layer is arranged in six rows of a line-shape. Next, the second insulating layer 14b is stacked on the first insulating layer 14a in the manner of covering the first coil layer 15a.
In a fourth step shown in FIG. 3D, the second coil layer 15b is formed in six lines on the second insulating layer 14b corresponding to the first coil layer 15a. Next, the third insulating layer 14c is stacked on the second insulating layer 14b in the manner of covering the second coil layer 15b, so that the insulating substance layer 14 including the first through third insulating layers 14a, 14b and 14c is formed in the manner of completely insulating the coil layer 15 of two stages and six lines.
Furthermore, in a fifth step shown in FIG. 3E, the upper magnetic substance layer 16 of amorphous materials is stacked in a predetermined thickness in the manner of further covering an exposed portion of the gap layer 13, the insulating substance layer 14 which is formed in the predetermined area of the gap layer 13, and the coil layer 15 which is covered by the insulating substance layer 14.
Finally, in a sixth step shown in FIG. 3F, the protective layer 17 of plastic or low-temperature melting-point glass materials, is stacked in the manner of covering the upper surface of the upper magnetic substance layer 16, thereby completing the material 10 of the thin-film magnetic head 10A.
The material 10 formed by the above steps, is cut in a predetermined shape shown in FIG. 2, thereby completing the thin-film magnetic head 10A as the product.
The material 10 of head 10A has three stages of the insulating layers and two stages of the coil layers which are formed between the insulating layers. In order to form each of the layers, there is used a thin-film formation technique such as sputtering and a vacuum evaporation and a thin-film treatment technique such as ion-milling or dry etching.
It is necessary for the conventional thin-film magnetic head 10A to form the lower magnetic substance layer 12 and the upper magnetic substance layer 16 which constitute a magnetic loop each having several ten micrometers thick in order to prevent the magnetic loop from a magnetic saturation. However, in case where the magnetic layers 12 and 16 have the thickness of this, respectively, because the layers have patterning accuracy of plus and minus 5 to 10 micra when patterning is performed to both layers 12 and 16, an accuracy of the outline size of the head as a product is remarkably reduced.
Accordingly, in the case where a track width of the thin-film magnetic head 10A is formed by patterning the lower and upper magnetic substance layers 12 and 16, the conventional magnetic head has the problem that it is difficult to obtain the high-accuracy of the track width.